Railway braking apparatus



Oct. 17, 1933.

H. C. CLAUSEN RAILWAY BRAKING APPARATUS 2 Sheets-sheaf. 1

Filed April 22 1933 INVENTOR Harold C.(lausen 021M144 HIS ATTORNEY Oct. 17, 1933. H. c. CLAUSEN RAILWAY BRAKING APPARATUS Filed April 22, 1933 2 Sheets-Sheet 2 B SMK @KBhDwK A RQMQ QN INVENTOR Harold QClausQn BY QRMIANMZ H16 ATTORNEY Patented Oct. 17, 1933 RAILWAY BRAKING APPARATUS Y Harold (l Clausen, SwissvaleQ Pa assignor to The Union Switch & Signal Company; Swissvale, v v Pa., a corporation of- Pennsylvania 7 w p g V ApplicationApril 22,1933. Serial- No-.'667, 384 p .22 Claims. (c1.3o;s '20) My invention relates to railway braking apparatus, and particularly. to braking apparatus of the type comprising wheel engaging braking bars located beside a track rail, and movable to- .lward and away from the rail into braking andnon-braking positions. More. particularly my invention relates to apparatus of the type described wherein the braking bars are arranged to be moved to their braking positions by means of one 10 or more fluid pressure operated'motors, and to be restored to their non-braking positions by suitable biasing means such as gravity. l 1

exhaust of fluid pressure from, the fluid pressure motor or motors of braking apparatus of. the type describedwhen the braking apparatus is to be utilized in connection with a duplex pressure fluid distribution system such as is disclosed and claimed in an application for LettersPatent of the United States, Serial No. 639,434, filed by Herbert L. Bone, on October 25, 1932, and one object. of my invention is to improve and simplify the control means disclosed in the said Bone application. 1'

Other objects or my invention will appear as the description proceeds. i

I will describe two forms of apparatus embodying my invention, and will then point'out the novel features thereof in claims. r

In the accompanying drawings Fig. 1 is a view,..

partly sectioned and partly diagrammatic, illustrating one form of apparatus embodying my invention. Fig; 2 is a view similar to Fig. 1', but

trated in Fig. 1, which modified form of apparatus also embodies my invention.

Similar reference characters refer to: similar parts in both views. l i

is secured to arail support 2 mounted on an. adjacent pair of the usual crossties 8, only one cross-' the rail 1 is a car retarder comprising two braking bars A and A located on opposite sides of the rail. Each of these braking bars comprises,

as usual, a brake beam 4 and a. brake shoe 5.

moved toward and away from the rail 1 through the medium of a lever'fi'which is pivotally mount:

ed at one end on a pivot pin 8 carried by the rail support 2, and a lever '7 which is pivotally-mount the lever. '7- and braking bar A is to the left oflthe showing a modified form of the apparatus illus- Referring to the drawings, the reference char acter 1 designates one track rail of a stretch of. railway track,: which track rail, as here shown;

tie being visible in the drawings. Associated with" The braking bars A and A are arranged to be ed intermediate its ends on the pivot pin= 8.':. The

lever 6 is inclined upwardly extends away from the rail 1 and is provided-in its upper surface with a groove 6 which receives the brakingbar A The one end 7 of the lever 7- islikewiseinclinecl .upwardly, and extends away from: the, rail 0o.- 1 at the opposite side of the railirom the-:lever 6*, and the other end '7 of the lever 'l is inclined downwardly and extends away from the rail l below the lever 6; The end 7 of the leven'l is" provided in its. upper surface with a groove-7 smv 66; ilar to thegroove G inthe lever 6,- whichgroeve receives the braking bar A. The parts areso prov portioned that if the outer or freeends; at the le ver's 6 and ,7. are moved apart,'the'bs'akingbur-rv will be moved toward the rail 1 into their efiee- 70;- tive or braking positions. Whenethezbrakingbarsoccupytheir braking positions, the brake shoes 5 willengage the opposite side faces oi agcar wheel traversing rail 1, and will retard the speed of the car. I'Ihecenter of gravity of the lever 6 andlbakingbar A is considerablyto theright oi? the pivot pin 8, so that this lever will normally tend to rotatexin a clockwise direction aboutthea pivot pin.- Similarly, the center of gravity o6 pivot'pin 8. so that this-lever will normally tend l to rotatelin a counter-clockwise direction about the pivotpin; Itwill be apparent, therefore, thafit-- when no force is applied tothe'free ends of the. levers 6- and. 7 to move them apart, the free ends of these levers will move toward each other. therebymoving thefbr'aking bars to their; ineflective or non-braking positions in vl'rhich they are illustrated in the'drawingsr .1

The 1evers16 and 7' are moved apart to move; the-,braking bars to theirlbraking' positions by means of a "fluid-pressuremotor M comprising a cylinder 9': containing a piston 10" winch drives, a piston rod 11. The cylinder 9-ispivotally con; nectedwith the freeend of the lever 6=by means of 'trunni'ons 12 formed on the side of the cylinder and extending; through bifurcations I-S'formecl: on'the lever 6, while the pistonwrod 1-1 is com-- nected; at its free end with theiree end Wot the. lever 7 by means of an; adjustable: eyebolt 1 4 andapivot pin 15. Fluid 'pressure. may be ad mitted tmthecylincler 9* between the upper end? of .the cylinder and the piston"'1-0" through: am opening- 16' which is threaded to receivea pipe. 17. When. fluid-pressure ,is admitted: to the cyls-t inder 9 through the-pipe 1 7' and openinggm l pistonllluwill bev forced downwardly cylinder. 9iu-pwa-rdly, thereby separatingithe 10-: verse and 7;. and hence moving the brak-ing barstoward their;effective O jbraking positigns it? no being obvious that when the braking bars are moved to their braking positions, they will exert a braking force which is proportional to the pressure of the fluid supplied to the cylinder 9. It should be pointed out that while in the drawings I have shown only one operating unit for the braking bars A and A in actual practice these braking bars are provided with a plurality of other similar units, disposed at spaced intervals along the bars, substantially as shown in an application for Letters Patent of the United States Serial No. 516,883, filed by Herbert L. Bone, on Feb. 19, 1931, for Railway braking apparatus. out, that as a general rule, the car retarder will consist not only of braking bars associated with one track rail, as shown in the drawings, but'also also of other similar braking bars associated with the opposite track rail as well, the length of the braking bars associated with both track rails being determined by the speed and the weight of the cars to be retarded, the lengths of the cars, the number of wheels on the cars, etc.

The motor'M is controlled by three magnet valves, designated by the reference characters V V and V ,'respectively,= and each comprising a'valve stem 18 biased to an upper position by means of a spring 19, and provided with a winding 20 and an armature 21. When valve V is 6- energized, as shown in the drawings, valve stem 18 of this valve moves downwardly against the bias exerted by the associated spring 19, and under these conditions, a pipe 22 which communicates with the pipe 1'1 is connected with 1 atmosphere, through a port 23, thus connecting the region ofcylinder 9 between the piston 10 andthe upper end of the cylinder with atmosphere. When valve V is deenergized, however, valve stem -18 of this valve is moved upwardly 6-? by the associated spring 19, and pipe 22 is then disconnected from port 23, so that the region of cylinder 9 betweenpiston 10 and the upper end of the cylinder is then disconnected from at- .mosphere. When valve V is energized, valve '1stem 18-of this valve moves downwardly, and a pipe 24 which communicates with the pipe 22 is then connected with a pipe 25 forming part of a low pressure fluid distribution system. This low pressure fluid distribution system is con- 6 stantly supplied with fluid pressure, usually air, from a relatively low pressure source, not shown in the drawings, and it follows that when valve V is energized, the region of cylinder 9 between piston 10 and the upper end of the cylinder is supplied with fluid'pressure from the low pressure system; When valve V is deenergized, however, pipe 24 is disconnected from pipe 25 and is.

connected with a pipe 26 which leads to the valve V When valve V is energized, valve stem 0 18 of this valve moves downwardly and connects pipe 26 with a pipe 27 forming part of a high pressure fluid distribution system, which. latter distribution system is constantly supplied with fluid pressure, usually air, from a relatively high pressure source. When valve V is deenergized, however, valve stem'18 of this valve moves to its upper positionand disconnects the pipe 26 from the pipe 27. It will be seen, therefore, that when valve V is energized and valveV is de- 7 i energized, the region of cylinder 9 between the piston 10 and the upper end of the cylinder is V supplied with fluid pressure from the high pressure system, butthat when valve V is deenergized, the supply of fluid pressure from the high It should also be pointedchamber 31 between the diaphragms 33 and 34 The pressure of the fluid in the low pressure system may be maintained at any suitable pressure, but for purposes of illustration, 1 will assume that this pressure is maintained at approximately 50 pounds per square inch. Likewise, the pressure of the fluid in the high pressure system may be maintained at any desired pressure but for purposes of illustration I will assume that this pressure is maintained at approximately 100 pounds per square inch.

The valves V are controlled in part by two pressure responsive devices P2040 and P each comprising a Bourdon tube 28 connected to the pipe 1'7, and hence subjected to the pressure of the fluid in the region of cylinder 9 between the piston 10 and the upper end of the cylinder. Each Bourdon tube 28 controls two contacts 2929 and 29-29 The pressure responsive devices P and P are so constructed that they will operate successively as the pressure of the fluid in the region of cylinder 9 between piston 10 and the upper end of the cylinder increases. For example, for all pressures below 20 pounds per square inch, contact 29-29 of each of these devices is closed. If the pressure exceeds 20 pounds per square inch, however, contact29--29 of device P opens, and if the pressure exceeds 30 pounds per square inch, contact 29--29 of device P closes. In similar manner, the pres- I sure device P is adjusted to open its contact 2929*? at '70 pounds per square inch, and to close its contact 2929 at pounds per square inch. Of course, these specific pressures are not essential, but are. only mentioned for purposes of explanation.

.The valves V are controlled by means of two pneumatically operated transfer switches S and 8*. Referring first to the switch S this switch comprises a housing 30 provided with a chamber 31 into the upper end of which a switch operating rod 32 extends; The lower end of the rod 32 is connected to two spaceddiaphragms 33 and 34 of difierent sizes, the diaphragm 33 being smaller than the diaphragm 34. The portion of the is constantly connected with. atmosphere by means of a port 35, while the portion of the chamber 31 below the diaphragm 33 is connected with the pipe 25 by means of a pipe 37, and the portion of the chamber 31 above the diaphragm 34 is connected with the pipe 22. It will be apparent, therefore, that the lower side of the diaphragm 33 is constantly subjected to the pressure of the fluid in the low pressure distribution system, while the upper side of the diaphragm 34 is subjected to the pressure of the fluid in the upper end of cylinder 9 of motor M. As will be seen from an inspection of the drawings'the two diaphragms 33 and 34 are normally bowed upwardly, and the parts are so proportioned that when the net force resulting from the difference between the pressure exerted on diaphragm 33 and the pressure exerted on diaphragm 34 is sufiicient to move the diaphragms, they will move with a snap action, and will under no condition stop in mid stroke. The relative sizes of the two diaphragms 33 and 34 are such that the diaphragms will snap to their lower positions when the pressure in the upper end of cylinder 9 reaches a value slightly below that in the low pressure distribution system. It will be apparent, therefore, that the diaphragms will not return to their normal positions after they have once been snapped downwardly until the pressure in the cylinder 9-.has been reduced a certain amount below that in the low pressure 150 distribution system. For example, the parts will usually be so proportioned thatwhen the pressure in the low pressure distribution system is 50 pounds per square inch, the diaphragmswillsnap to their lowermost positions as soon as the pres= then engage the fixed contact members sure of the fluid in cylinder 9has increased to about 48 pounds per square inch, and will subsequently remain in their lowermost positions until the pressure in cylinder 9 has been reduced to approximately pounds per square inch. The" upper end of the operating rod 32 carries a contact member 38 which cooperates with three. fixed .Iwardly and are designed to operate at somewhat different prcssuresfrom the pressures at which the switch S operates,"as I will explain presently. The region of diaphragm chamber 31 of this switch below the diaphragm33 iscon- Jnected with the pipe 22 by means of a pipe 42; so

that the lower side of the diaphragm 33 is constantly subjected to the pressure of the fluid in the cylinder 9. The region of diaphragm chamber 31. above the diaphragm 34 is connected with f "jthe pipe 25 by means of a pipe 43, and it follows.

that the upper side of the diaphragm 34 is con stantly subjected to the pressure of the fluid in the low pressure distribution system. The parts are so proportioned that when the pressure in I ,the upper end of cylinder 9 increases to a value:

which is a predetermined amount above that in the low pressure system, the diaphragms 33 and 34 will snap upwardly, and that when thepres sure in the cylinder 9 is subsequently decreased .ito a predetermined pressure which is slightly above that in the low pressure system, the diaphragms will snap downwardly to the positions in. which they are shown. have snapped downwardly, they will, of course,

"remain in their lowermost positions until" the pressure in the cylinder 9 is again increased to a value which is high enough to, cause them to snap upwardly. For example, the parts will usually be so proportioned that when the pres ,sure or" the fluid in the low pressure system is pounds per square inch, the diaphragms 33' and 34 will snap upwardly when the pressure or: the fluid in cylinder 9 increased to approximately pounds per square inch and will subsequently remain in their upper positions until the pressure of the fluid in cylinder 9 has again decreased to app'roxiznately52 poundsper square. inch. It is, of course, understood that the specific pressures mentioned in describing the operation 7 of the switches S and are notnecessarily'the exact pressures at which operation of these switches will occur, but are stated for purposes of illustration only. The operating rod 32 of the switch S controls two contacts 39- 384land 39-38- l0 which are similar in all respects to the corresponding contacts of the switch S The valves V V and V are further controlled by a manually operable lever L capable of assuming five positions,indicated by the reference char.- acters p top inclusive. Attachedto the lever L.

After the diaphragms isa contact arm 44 which is selectively moved into engagementwith aplurality of fixed contacts 45 to '49, inclusive, in response to movement'of the.

lever to its various positions;

Lever L will. usually] be located. at a point remote from the braking apparatus, as in the con trol cabin of a classification yard. car retarder,

system, and will be: connected withv the braking?) apparatus by means of line wires'extending from the. control cabin: to the braking apparatus.

I As shown in the drawings, lever L occupies its p or .fofi? position, and under these conditions,

a circuit is, completed for. valve V which cir'fcuit.

passes from a suitable source of current, here shown asa'battery B, through wire 50,.c0ntact I willnow assume that thexoperator wishes to" cause the car retarder to'exert a comparatively light braking force. To. do this, he moves lever L from'its p to'its p position; thereby opening contact 4445 of the lever and closing contact,

44--46. The opening of contact 44-45 interrupts the circuit whichwas previously closed for valve V at this contact, and valvev therefore becomes deenergized. and disconnects pipe 22 from atmosphere, thus disconnecting the region of cylinder 9 of motor M between piston 10 and theupper end of the cylinder from atmosphere. The closing of contact,44-46 of lever L completes a circuit'for valve V and current flows from battery'B through wire 50, contact 4446 of level L,

line wire 55', contact 29..29 ofpressure responsive device P 4", wires 56 and 57, winding 20 of valve V wire 53, and line wire 54' back to battery B. Valve vltherefore becomes energized,- and connects pipe 22' with pipe 25, sothat fluid pressure from, the; low pressure distribution systern isfnow supplied to the upper end of cylinder 9 of :motor The fluid pressure thus supplied tocylinder .9 ,forcespiston 1'0; downwardly and cylinder 9 upwardly in the manner previouslydescribed, thereby moving: thebraking bars towardtheirtbraking.positions. When the pressurein cylinder 9' increases to,20 pounds per square 5inch; contact 29'29 of pressure reesponsive device P will open'and will interrupt the cir'cuitjust traced for valve 'V Valve V will then become deenergized and will cut off the supply of: fluid pressure to cylinder 9 until the p'ressura'a of the ,fiuid' again decreases below 20.- pounds ':per square inch; If the pressure of the fluid ingthe upper end of cylinder 9 increases to 30 poundsper square'inch for any reason, contact 29 29 .;of pressure responsive device P2040 will become closed, and will complete another circuit for valve V this latter circuit passing from battery B through wire 50, contact 4446 of lever L, line wire .55, contact 29-i 29 of pressure responsive device. P wire 58,- contact 39'-3841 of'transfer switch S3, winding 20' of valve V wires 52 and 53, andline wire 54 back to battery 13.: Valve V will then become energized and 'willvent fluidfromthe upper end of fluid in this region of the cylinder again decreases to 30 pounds per squareinch, at which time contact 29--29 of pressure responsive device P will open and will deenergize valve V It will be seen, therefore, that when lever L occupies its 0 position, the braking bars will be held in their braking positions by a pressure of between 20 and 30 pounds per square inch.

I will next assume that the operator desires to cause the braking bars to exert a somewhat higher braking force He therefore moves lever L from its p to its p position. Under these conditions, valve V becomes energized, and constantly remains energized as long as the lever remains in its p position, by virtue of. a circuit which passes from battery B through wire 50, contact 44-47 of lever L, line wire 59, wires 56 and 57, winding 20 of valve V wire 53, and line wire 54 back to battery B. When valve V becomes energized, fluid from the low pressure source is, ofcourse, supplied to the upper end of cylinder 9 of-motor M, and since this valve now remains energized, it will be apparent that the pressure of the fluid in the upper end of cylinder 9 will build up to the full line pressure of the low pressure source. It follows, that under these conditions, the braking bars will be held in their braking positions by the. full pressure of the low pressure source. Shortly before the. pressure of 1; the fluid in motor M reaches the full pressure of the low pressure source, the diaphragms 33 and 34 of transfer'switch S will snap downwardly to their lowermost positions, thus opening contact 3938-40 of this transfer switch and 0105- ing contact 39-3841.

contacts under these conditions, however, will have no immediate effect upon the operation of the remainder of the apparatus.

If a still higher braking force is'desired, the

operator will move lever L from its p position to its p position. When he does this, all circuits previously traced for the valves V and V will be interrupted, and a circuit for valve V will become closed, this latter circuit passing from battery 13 "through wire 50, contact 44- 48 of lever L, line wire 62, contact 2929?- of pressure responsive device P f' wires 60 and 61, contact 393841 of transfer switch S winding 20 of valve V and line wire 54 back to battery B. Valve V will therefore become energized, and since valve V is now deenergized, fluid pressure from the high pressure source will be supplied-to the upper end of cylinder 9 of motor M. When the pressure in the upper end of cylinder 9 increases to 60 pounds per square inch, the diaphragms of transfer switch S will snap to their uppermost positions, thus opening contact 39- -3841. of switch S3 and closing contact 39-38-40 of switch S The operation of these contacts .under these conditions, however, will have no immediate effect on the remainder of theapparatus. When the pressure of the fluid in the upper endof cylinder 9 of motor M increases to 70 pounds per square inch, contact 29-29 of pressure responsive device P will open, and will interrupt the circuit just traced for valve V Valve V will then become deenergized, and will cut off the supply of fluid pressure to the upper end of cylinder 9 of motor M. If the pressure in the upper end of cylinder 9 of motor M increases to 89 pounds per square inch, contact 29--29 of pressure responsive device P' will become closed,

I and will complete another circuit for valve V The operation of these Wire 54 back to battery B. ValveV will therefore become energized, and since the pressure of the fluid in the upper end of cylinder. 9 of motor M is now above that of the fluid in the low pressure system, fluid will be vented from the motor into the low pressure system until the pressure decreases sufliciently to permit contact 29-29 of pressure responsive device P to open and deenergize valve V It follows, therefore, that when lever L occupies its p position, the braking bars will be held in their braking positions by a pressure of between 70 and pounds per square inch.

I will now assume that the operator, instead of moving lever L to its 10 position from its p position, moves the lever to its p position directly from its p or p position. Under these conditions, when the lever first reaches its p position, the diaphragms of transfer switch S will still occupy their upper positions so that contact .39- 38-40 of this switch will be closed and contact 39-384l will be open, and as a result, a circuit will now initially become completed for valve V passing from battery B through wire 50, contact 44-48 of lever L, line wire 62, contact 29.29 of pressure responsive device P wires 60 and 61, contact 393840 of transfer switch S wire 63, winding 20 of valve V wire 53, and line wire 54 back to battery B. Valve V will therefore become energized and will admit fluid to the upper end of cylinder 9 of motor M from the low pressure distribution system in the manner previously described. When the pressure of the fluid in motor M increases to 48 pounds per square inch, the diaphragms of transfer switch S will then snap downwardly to their lowermost positions, thus opening contact 3938-40 of switch S and closing contact 39-38-,-41. The opening of contact 3938-40 will interrupt the circuit just described for valve V while the closing of contact 393841 will complete the previously described circuit for valve V including this contact, contact 35 48 of lever L, and contact 2929 "of pressure responsive device P"- Valve V will therefore become deenergized, and will cut off the supply of fluid pressure to cylinder 9 of motor M from thelow pressure distribution system, and valve V will become energized and will admit fluid pressure to cylinder 9 of motor M 9 of motor M until the pressure in the cylinderincreases to 48 pounds per square inch, after which valve V will become deenergized and valve V will become energized. When valve V becomes energized, any-further fluid which is supplied to motor M will, of course, be supplied from the high pressure distribution system.

If the operator desires to cause the brakin bars to exert their maximum braking force, he will move lever L to its 10 position. When he does this, if the lever had previously occupied its p or 9 position long enough to permit the pressure of the fluid in the upper-tend of cylinder 9 of n otor M tosbuild up to the value at which transfer switch S opens its contact 3840 and closes its: contact 39 3841, valve V will immediatelybecome energized and vwill admit fluid pressure to the upper-end of cylinder-Q of motor M- fIOHl-thehigh pressure distribution system, the circuit for .v alvev? under these conditions passing from battery B through wire 50, contact 4449 of lever L, "linewire 64, Wire 61, contact 39,38-41 of transfer switch S winding 20 f valve V and-line wire 54 back to battery B. If, however, when lever L is moved to its p-iposition, the lever had previously occupied its p or; p position," so that when the lever reaches its piposition, the pressurein the upper end of cylinder 9 of motor M is still below -the pressure atzwhich the transfer switch S opens its contact"39 3840 and closes its contact 39 38'-4l, valve V will -thenbecorne energized and will admit fluid pressure to cylinder 9 'of motor M; from the low pressure distribution system until the pressure in the cylinder builds upto the pressure. at which transfer switch-S opens its-contact 39- 3840:and closes its contact 39-38-41, -whereupon, valve V will then traced above.

these latter conditions. passes fromibattery B, through wire 50,,contact 44- 49 of lever L, line become energized by virtue of the circuit Just The circuit for-valve V under wire 64, wire; 61, contact 39 3840 of transfer switch s wire 63, winding 200i valve V wire,

53, and-line wire 54 back to batteryB. It will be apparent from an inspection. of the drawings that after valve V once becomes. energized under these conditions, it will subsequently remain en ergized :aslong as lever Lremains in its p position, so that the braking bars will be held in their braking positions-by the ,fullpressure'of the high pressure distribution systernQ- I I will now assume that lever L has been moved "to. its p positionto causethe braking bars to exert their maximum braking force, and that the operator wishing to reduce the braking force exerted by the braking bars, moves the lever to its p position. This movement of'the lever will interrupt the circuit which was previously closedfor valve-V and will. complete a circuit for'valve W which glatter circuitzpassesimm bat-- 'tery B through wire 5O,' contact444 6 ot lever L, line wire 55 contact 29- -29, of pressure responofjtransfer'switch S wire 57, winding of valve V wire 53, and linewire 54 back to battery B; Valve V will therefore become deenergizedand willdisconnectfcylinder 9 from the high pressure distribution ,system, and valve V will become energized and will connect cylinder 9, with, the

low pressure distribution system. When cylinder 9 becomes connected with the low pressure distributionsystem,v the pressure of the fluid in the motor will, -.of course, Abe-above thatin the low pressure system, and 'fiuid from cylinder 9 will therefore be vented into the low'pressure dis tribution system; As soon as the pressure ofwthe I fluid in cylinder 9 has decreased to 52 pounds per square inch, transfer switch S will open, its contact 393$-40 and close its contact 39 -38141, thereby interrupting the-circuit just: traced for valve. V and completing" the previously described circuit for valve "J including contact 39-38.-41 of switch S and c0ntact "2 9- 29 of pressure responsivedevice w e l,v Valve: V will then become deenergiz-ed and will; disconnect, cylinder 9 from the low pressure 'distribution system,

1or."o position. When he doesthis, if thep essure of 'the flui'd i'nthe upper end-of cylinderl9 L, line wire 51,. contact 39-73840 tr transfer to open its contact 39-3 41 'and closellitsicontact 3938-. [aslsoon' the pressure motor .M has decreasedto 40 pounds-persquare inch.

valve V will become energized and will connect f cylinder 9 with atmosphere. When the pressure of the fiuidf in cylinder 9 has decreasedto 40 pounds per square inch,'itr ansfer switch S},wi1l

close its contact 39'-+3841,butfthejoperation of this switch under these conditionsjwill-have I Qmoved to its p j-position ,from""itsp, position.

Iwill now assume that the'bralringlfbars are .95

in their braking positions, and" that the Operator wishes to restore them to their non-braking positions. He will therefore movejlever L1 to; its p of, motor M is then above' the pressure latwhich transfer switchS opens its contact' 39- r-3Hll and closes its contact 39,- 38 .,.40,,.,as .Will he the case as lever L previously occupied its pfljor 12 position, valve Wwill first become energized and will ven't fluid from motor, M into-the. low, pres sure distribution systeirfuntil the pressureiofthe fluidjinr the motor decreases to the'pr'es'sure' at which transfer switch 8 .opensIits contact 39; 38 -40 andcloses its L-contact 3938f3i 1', where- 1m upon valve V will become energized and will vent the remainder of the fluid in the'motor to atmosphere, If,' ow ver, when ,the .lever. is 'jIno'ved-qto its p position, the pressure of the fluid'in'cylinder 9 is below the pressure at which; transfer switch 's= opens its Conta t 39+,38,- -4 0fand,cl oses1its 5" contact 39-38-41,;asw-il1 .be thefc ase lever previously occupied itsQpt'or p po'sition, valve V will immediately, become energizedand will ventfluid. iromlcylinder jtoiatmo piier The circuit over", which ,valveV becomes energized under the above. conditions P 5565 from battery B through wire 50,'contact -44- -l-.45fof lever switch s wire 57, winding.20 f valve wire 53,- and-linewire 54Yback to battery B, The circuit cover which valve V becomes. energized under-the above; conditions has [previously 3 been I described and need not therefore be.re peated here: ,It should be pointed out that if the pressure'of the 10 fluidli n v cylinder 9 of motor M has been above the pressure at which transfer switch S opens its vcontact 39,38 .40 and'close's its (immense-,-

38 -4 1 at any timei prior' to (the movement "of lever L toits p? position, this switch, will I operate AS the P e s re n =v inde Zo a m w; creases, the braking barslwill returnto the nonraring'positidi s bygravity,{a'ridwhen' th H Iakn z 'a s e t e r s nrb a n j iti s; 51 parts will be restored toKthepQsitiorisl they are shown in ,the di'awings.

g It shouldbe particularlypointedioutgthatwhile Lin thejforeg'oing description} havedes ba operation of the apparatusfforf onlyia few the,

principal movementsof lever. the operation of i .the apparatus for h g emsin e gor.tnejioq sme Wei-Hi lever Loccupies its position, in'which position itis illustrated in the drawings, sorthat contact.

arm 44 engagesfixed contact 45, contact arm 44% will engage fixed contact 45 and when lever L occupies its p? positiomso that contact arm 44 engages fixedcontact 46, contact arm 44 will engage fixed contact 46 Furthermore, asshown in Fig. 2, the circuits for controlling the valves Vhave been modified somewhat, and rectifiers have been included in certain ones of these circuits inorder to decrease the number of line wires 7 between the control point and the braking apparatus, and to prevent improper operation of the valves V, in'the event that the contacts of one of the pressure responsive devices'becomes shortcircuited, asv by condensation of moisture on the contacts. The operation of the apparatus shown in Fig.

'2 is as follows: Whenjlever L occupies its p or off position, valves V and V are both'deener- 'gized, and valve V is energized'over, a circuit which passes from battery B through wire 50,

contact 4445 of lever L,line wire 51, an asym metric unit R in its low resistance direction, wire 65, contact 39-38-41 of transfer switch "S winding 20 of .valve V wires 52 and 53, and line wire 54 back to battery B. Since valves V and V? are deenergized, the supply of fluid pressure to cylinder 9 of motor M fromboth thehigh and low pressure distribution systems is cut off, and since valve V is energized, the upper end of cylinder 9 of motor M is vented to atmosphere. The braking'bars are therefore held in their nonbraking positions by gravity. Furthermore, since the upper end'ofmotor M is vented to atmosphere, contact3938.40 of transfer switch S contact 3938-41 of transfer'switch' S and the contacts 29-29 of the pressure responsive devices P are all closed, while contact 39-38-'41 of transfer switch S contact 39'3840 of transfer switch S and contacts 29*29 of the pres-' sure responsive devices P are all open.

If, now, lever L' is moved to its p position, valve V will become-deenergized, and valveV will become energized over a circuit which passes from battery B through wire 50, contact 44- 46 of lever L, line wire 55, contact 29-29 of pressure responsive. device P wires 56 and 5'7, winding 20 of valve V wire 53, and line 'wire 54 back to battery B, The deenergization of valve V will disconnect the upper end of cylinder 9 of motor M from atmosphere, while-the energization of valveV will connect the upper end of cylind'er 9 with pipe 25, so that fluid pressure will then be supplied to cylinder'9 from 'the low pressure distribution system, thus moving the braking bars to their braking positions. When thepressure of the'fluid in cylinder 9 increases to 20 "pounds per square inch, contact 2929 of pressure responsive deviceP will.

open and will deenergize valve'v and ifthe pressure of the fluid in cylinder 9 increases to 30 pounds per square inch, Contact 229 -29 o 1,931,142 described, and it is believed that this oper t o pressure responsive device P will become closed and will complete another circuit for valve V this latter circuit passing from battery B through wire'50, contact 44-46 of lever L, line wire 55, contact 29-29 of pressure responsive device P wire 66, asymmetric unit R in its low resistance direction,' wire 58, contact 39-3841 of transfer switch S winding 20 of valve V wires 52 and 53,- and line wire 54 back to battery B; Valve'V will therefore become energized, and willvent'fluidfrom cylinder 9 until the pressure of the fluid in the cylinder.

decreases sufficiently to cause contact 2929 of pressure responsive device P to open and 'deenergize valve V Itwill be seen, therefore, that with the apparatus shown in Fig. 2, when lever L is moved to its p position, the braking bars will be held in their braking positions by a pressure of between 20 and 30 pounds per square inch inthe same manner as 'withthe apparatus shown in Fig. 1.

If lever L is moved from its p position to its 12 position,'.the circuit last traced for valve V will; become interrupted, V and another circuit for valve V will become. closed,this latter circuit passing from a suitable source, here shown as a battery B through line wire' 54, wire 53, winding 20 of valve V wires 57, 56 and-67, an asymmetric unit R in its low resistance direction, line wire 51, wire 68, contact 44 -47 of lever -L, and wire 69 back tobatteryB *It will be noted that this circuit iscontrolled entirely by contact 4 95-47 of. lever L, and it follows therefore that valve V will now remain energized as long as lever L remains in its p position, and the braking bars will therefore be held in their braking positions under these conditions by fluid'at the fullpressure of the low pressure distribution system. Shortly before" the pressure of the fluid in cylinder 9 of motor- M reaches the full pressure of the low pressure distribution system, transfer switch S will open its contact 393841 and close'its contact 39-3840 in the manner previously described. The operation of these contacts under these conditions, however, will have no immediate effect on the re- "mainde'r of the apparatus.

' I will next assume that lever L is moved from p its' p position to its 9* position. Under these conditions, valve V will become deenergized and valve V will become energized, thus'causing fluid "pressure to be'suppliedto the upper end of cylinder 9 of motor M from the high pressure distribution system. The circuit over which. valve V becomes energized under these conditioris passes from battery B through wire-50, contact 44-48 of lever L, "line wire}62, wire '71,

contact 295-29 of pressure responsive device P' wires 60 and 61, contact 39-38--41"of transfer switch S winding 20 of valve V and" line wire 54 back to battery B. When the pres sure of the fluid in the'u'pper end of cylinder 9' increases to 60 pounds per square inch, transfer switch S will open its c0ntact 3933+'-41and close .its contact 3938-40. The operation of 'these contacts, however, will have no immediate effect on the remainder of the apparatus. When the pressure of the fluid'in the upper end'of cylinder 9 increases to '70 pounds per. square inch, contact "2929 of pressure responsive device P will open, and will interrupt the circuit just traced'for valve V Valve V will then become'deenergized, therebycutting off the sup- ,ply of fluid pressure to the upper end of cylinder"9. If the pressure in'the upper 'end of of pressure responsive device cylinder 9 increases to 80 pounds per square inch, contact 29-29 of pressure responsive device P 9 will become closed, and will complete another circuit for valve V which vcircuit passes from battery B, through wire 50, contact 44-48 of lever L, line wire 62, wire 71, contact 292 9 of pressure responsive device F lwire 66,

asymmetric unit R in its low resistance direction, wire 58, contact 39 38--40 of transfer switch 8*, wire 57, winding "20 of valve V wire 53, and line wire 54 back to batteryB." Valve V willtherefore become energized and will vent fluid from the upper end of cylinder 9 into the low pressure distribution system. Valve W will continue to vent fluid to the low pressure system when the lever reached its 11 position, and under these conditions, valve V will become energized over a circuit which passes from battery B through contact 44-48 of lever L, 'line wire '62,

wire 7l, contact 29---29 of pressure responsive Y will subsequently remain energized as long as the device P wires and 61, contact393840 of transfer switch's winding 20 of valve V wire 53, and line wire 54 back to battery B. Fluid pressure will therefore be supplied to cylinder 9 of motor M from the low pressure source until the pressure of the fluid in the motor increases to 48 pounds per square inch. Whenlthis happens, switch S 'will open its contact 3938j40, and close its contact 393841, thereby interrupting the circuit which was previously closed for valve V and completing the" previously. described circuit for valve V After valve V once becomes energized, the operation of the apparatus will then be the same as when lever L is moved to its p position from its p position. It

follows, therefore, that if leverL is-movedto its 1: position directly from its p or 12 position,

cylinder 9 of motor M will be supplied with fluid from the low pressure distribution system until the pressure of the fluid builds up to substantially the pressure of the low pressure distribution sys- Jt'emQafter which themotor will then be supplied with fluid pressure from the high pressure distribution system until -the pressure increases to the value at which contact 29-49 of pressure responsive device P"* opens.

motor M under the conditions just described increases to pounds persquare inch, valve W will become energized and will'vent fluid from the motor into the low pressure distribution system until the pressure in the motor again decreases to 80 pounds.- 7 e i c If lever L is first moved to its-p or 1 position long enough to permit the pressure in the upper end of cylinder 9 of motor M to build up to the pressure at which contact 39-"-3$--40 of transfer switch S opens and contact 39'38'-41. closes,

and the lever is then moved to it-sp position, valve V will immediately become energized and lever remains in its p position, by'virtue of. a

circuit which passes from battery B through line wire 54,'winding' 20 of valve V ,.contact 39-38-7 41 of transfer switch S1, wire 61,"asymmetric imit R in its low resistance direction, line wire 62, wire 70, contact 441 49 of lever L, and V, wire '53: and line wire- 54 'backto b'attery B. 1156. r

Furthermore, if the pressure in the upper end of cylinder 9 of source as long as thelever remains initsp position. If,however, lever L is'moved to its 11 position' directlyfrom itsp 'or 11* position so that contact 39 39-40 oftransfer switch S is still -wire' 69'baclr to battery B Unden these conditions, therefore, motor .M will be constantly. suppliedwith fluid pressure from thehigh pressure closed when the lever-reaches its 41 position, I

valve W will flrst become energized and will admit fluid pressure to the upper end of. cylinder f motor M from the low'pressuredistribution' system until'the pressure vinthe motor'in'creases "to the pressure at which transfer switch S opens its contact 39-1-3840 and closes its' contact 39-38'4-1, after: which valve V will become deenergized-and valve V? will ,become energized, thereby cutting off the supply oftfluid pressure to cylinder 9 from the low pressure distribution system, andadmitting fluid pressure to cylinder 9 from thedhigh pressure distribution system. The circuit over which; valve V becomes energized under these latter conditions may be traced from battery B through linev wire 54, wire 53, winding '20 of valve V, wire 63, contact ;39 36-40 of transfer switch S wire 61, asymmetric unit R in its low 'resistance sdirection, wires 62 (and 70, contact M -49 of lever L and wire'69 back to battery B The circuit over which valve V becomes energized under these latter conditions is the same as was previously described when lever. L was moved tov its p position from its p position. After valve V3 once becomes ensequently remain "energized' l-thus causing the motor to be suppliediwith" fluid from the high I: after lever L has 'bee n moved to its 1 posi-.

tionthe lever is moved to itsipz'ipdsition, valve N will-become deenergized and rvalveV3 will become;1,15

energized. The circuit over iwhichvalve V becomes energized under-these zconditions' passes from battery 3 through "wire'. 50-,contact 44-746 -of lever L, linewire 55,: contact 2929 of pressure responsive 1devicef' P"-"- wire 66,: asym- *metricunit R -in its low resistance directiomwire 58, contact 39--38 4O of transfer 'switcliS winding20 of valve v wire .53,' an'd line wire,54 back to battery B; When valve V 'becomesxenergized, fluidpressure-will, of course, be vented from cylin- 325 der .9 into the'low pressure distribution system.

Fluid pressure will continue to be vented into the low pressure distribution system under thesec'onergized under these latter conditions, itwill .sub-

no pressure distribution'sys'tem in themanner previously described. l

ditions until-the pressure in cylinder 9 decreases to 52 poundsper square lnehat which time trans fe'rswitc'h s willopen its 'contact'39 -.38+40Iand close its contact 39-381,4 1', thereby interrupting the circuit just traced'forva'lve .V'-.'.;-and' completing thepreviously described 'circuiti'fof vah e' V "After the circuit for Ivaive V becornes closed; under these conditions thei'apparatus will then function in=the samefmanner asjivlfxen leverLtwas moved to itsp position fromits'plpositionn pleted for 'valve'V? which passes from battery--13 wire 51;:asymmetric: unit R in its low resistance *through wire- 50, contact; 444-45 of lever L, line -.direction,:lii1e wire .65,"-conta ct see-384m of transfer switch S .w'ire 57,.win'ding 20; of valve shown in the drawings. I It should be pointed out that with theapparatus braking bar extending parallel to a track rail,

Fluid will the refore be vented from cylinder, 9 of motor M into' the low pressure distribution system untilthe pressure decreases to 52 pounds per square inch, whereupon the resultant operation of .pounds per square inch, transfer switch S will open its contact 3938-'-41 andv close its contact 393840, but the operation of these contacts under these conditions will have no effect on the remainder of the apparatus. As the pressure in the upper end of cylinder 9 continues to decrease, the braking bars will return to their non-braking positions by gravity, and when the braking, bars 'reach their non-braking positions, all parts will then be restored to the positions in which they are as shown inFig, 2, if the asymmetric unit R were omitted and the contacts of oneof the pressure responsive devices P becameshort-circuited, as byra drop of water, when lever L occupies its 10 or ".ofl. position, the valves V and V would then both become energized and there would be a continuous exhaust of fluid pressure from the low pressure distribution system to, atmosphere. The. asymmetric unit R however, prevents thisfrom happening because it prevents the flow of current from wire to the contactsof the pressure responsive devices, and'hence to the valve V under these conditions. The asymmetric units R1 and R are provided to permitthe selective control of the valves V 'and V over the same pair of line wires 51 and 54 in the p and p positions,-'respectively, of the'lever, bylreversing the polarity of the current supplied to the line wires 51 and 54 while the asymmetric unit R permits the desired selective'control of the valves V and V in the p and p positions of lever L't'o be obtained by reversing the polarity of the current supplied to the two line wires 62 and 54.

Although I have'herein" shownandf described only two forms of railway braking apparatus embodying my invention, it islunderstood that various changes and modifications may be made a fluid pressure motor-for moving said braking bar toward said track rail to braking positions, a first. pipe connected with a source of relatively low pressure'fluid, as'econd pipe connected with a source of relatively high pressure fluid, a-pneu- .matic't'ransfer switch responsive tothe pressure of the fluid in'said motor'and provided with a normally closed contact which becomes opened when the pressure of the fluid in said motor increases to a pressure which is somewhat-less than the pressure of said low pressuresource and with a normally open contact which becomes a closed when said normally closed contact! becomes opened, means controlled by saidnormotor with said second pipe. 7

- 2. Railway braking 1 apparatus comprising a braking barextendi'ng parallel toa track rail, afluid pressure ,motor for'moving said braking bar toward said track rail tov braking positions, a first pipe connected with a source of relatively low pressure fluid, a second pipe connected with;

a sourceof relatively high pressure fluid, a'pneumaticv transfer switch responsive to the'pressure of the fluid insaid motor and provided-with a normally closed contact'which becomes opened when the pressure of the fluidin said motor in- 1 creases to a pressure which is somewhat less than the pressure of. said :low pressure source and with a normally open contact which becomes closed when said normally'closed contact becomes opened; a manually operable contact, means controlled by said manually operable contact and said normally closed contact .for connecting said motor with said-first pipe, and

means controlled by said manually operable contact andsaid normally open contact for con necting said motor with said second" pipe.

- 3. Railway braking apparatus comprising a a fluid pressure motor for moving said braking ibar' toward said track rail to braking positions,

a first pipe connected with -a source of relatively low pressure fluid; a second pipe connected with a source of relativelyhigh pressurev fluid, a first magnet valve for connecting said 'motor'with' said first pipe, a second magnet valve for connecting said motor with said secondpipe, a pneu- 7 matic transfer switch responsive-to the pressure of the, fluid in said motor andnprovided with a normally closed contacts-which becomes opened when the pressure of the fluid in said motor increases to a pressure which is somewhat less than the pressure of said low pressure source and with a, normally open contact which becomes closed when said normally closed contact be- :comes opened, and means controlled by, said two contacts for selectively controlling said two magnet valvesi r l g 4. Railway braking apparatus comprising a braking bar extending parallel to a'track' rail,

a fluid pressure motor for moving said braking bar toward said track rail to braking positions, a flrstlpipe connected'with a source of relatively low pressure fluid, asecond pipe connectedwith a source of relatively highpressure'fluid, a first magnet valve for connectingsaid motor with, said first pipe, a second magnet valve for connecting said motor with said second pipe,'a pneumatic transfer switch responsiveto the pressure of the fluid in said motor and provided with a normally closed contact which becomes opened when the pressure of the fluid in said motor increases to a pressure which issomewhat less than the pressure of said low pressure source, and with a normally open contact which becomes closed when said normally closed contact becomes afiuid press'ure motor form'ovingj said braking bar toward said track: rail to braking positions,

a first pipe connected witha source of. relatively -low pressure fluid, a second pipe connected with "a source of relatively high pressure fluid, a first magnet valve for connecting said 'mot'or with said first pipe, a second magnet valve .for convnecting-saidemotor with said second pipe; a pneumatic transfer switchresponsive to the pressure becomes opened, means for at times energizing said first magnet valve when said normally closed contact is closed, and means effective-,after sailcl first magnet valve has been energized for subsequently automatically energizing said second valve if the pressure, in said motor. increases-to the pressure at which said normally .closed'contact becomes opened and said normallyopen contact becomes closed.

6.- Railway braking apparatus comprising a braking bar extending parallel .toa track r'ail, a fluid pressure motor for moving-saidhraking bar toward said track rail to -brakingv positions, a first pipe connected with a source of relatively low. pressure fluid, a second pipe connected with a source of relatively high pressure fluid,-a first magnet valve for connecting said motor with said firstgpipe, a second magnet valve 'iorconnecting said motor with said second pipe, a pneu: matic. transfer switch responsive to thepressu're of the fluid in said motor and provided with a comes opened; means controlled :by said normal- 1y closed contactjfor at timesxenergizing-isaid first valve, and means controlled by said normally'open contactand effective at times after said first valve has been energized for energizing said second valve if thepressure in said motor increases to the pressure at which-said normally closed contact becomes opened and said nor: mally open contact becomes closed. v p g '7.-Railway braking apparatus comprising ;a

braking bar extending parallel to a trackerail,

afluid pressure motor for moving said braking bartoward said track rail to brakingpositions, a firstpipe connected with? a source of relatively low pressure fluid a second pipe connected with a source of relatively high pressurefiuid,-= a flrst magnet valve for "connecting said motor with said flrst'pipe; a second magnet,valveior. con: necting said motor with said second pipe, a pneumatic transfer jSWitCh responsive to the pressure 7 of the fluid in said motor and provided with a normally closed contact which becomes opened when thepressure of the fluid insaid motor increases toaa pressure which is somewhat less than the pressure of said low pressure source and with a'normally open contactwhich becomes closed when said normally closed contact becomes opened, a manually operable contact, ,a circuit for said first valve including said manually operable contact and said normally closed A contact, and a circuitfor-said second valve in- 4 cludingxsaid manually operable contact and said ence in, pressure ,between the fluid insaid motor and insaid firstpipeand providedwith a con-; tact operating, memberwhichmoves fromone position tOBIlOthBIf position with a-snapactionwhenthe difference in pressure between the fluid in said-,motor and in-said first pipebecomes less than :a, first predetermined amount and which returnsto said one position with a snap action when the difference in.-pressure between the fluid in said motor-and-in saidfirst: pipe becomes greater .:than asecond predetermined amount which is. lar er -than isaid first predetermined amount, said transfer switch also beingprovided with a first contact which is closed when; and only .when-saidcontact operatinggmember occupies-said one position and with a second con-, tact which isv closed, when and only when said contact operating-member occupies said other position, andmeans, for at times connecting said motor,wit h=saidg first or said second pipe .according, as said-first or ,s aid secondwcontact is closed, x v

:9- Ra lwa ak ap a atus c mprising1v a braking barextending parallel; toav track rail; a fluid pressuremotor ior. moving said brakingubar toward said track rail ,to-braking positions, a:flrst pressure :fluid, asecond pipe connectedv witha pipe connected withsa sourceof relativelylow I sourceof relatively high pressure fluid, agpneumatic transfer switch responsive to the, difference in pressure between'the fluid in'saidmotorand in said first-pipeand provided with a contact operating member -which moves fromxonecmosie tion to another positionwitha snap action when the difierenceinj pressure between the fluid ,in

than 5 a first predetermined amount and which returns to said one position with a; snap action when the difference in pressurabetweentthe fluid in said::motor andu'in said? first gpipeg becomes greater than a; second, predetermined amount which; is larger, than said, first: predetermined amount, said transfer switch: also bein provided with a first, contact, which is closed when said contact-operating memberoccuPie-S1Said oney'position and with a SBCOHdiCODtaQlZ whichisclosed when 1 said :contact operating member occupies said otherposition, a manuallygoperable contact,

means controlled by; said, manually operablescontact and said vfirst contact for connecting said motor with-said first pipe andmeans controlled by-said manually-operable contact andwsaid sec- 0nd contact for connectingsaidmotor withwsaid second pipe.

10; Railway brakin apparatus, a

braking bar extending .parallelmto a track rail, a fluid; pressure motor for moving saidabraking bar toward said tragek :rail tobraking positions,-

a first pipe connected with a source of relatively low pressure fluid,- a second pipe'connectedg with a source of relatively high pressure fluid, a first magnet :valveior ;connecting.said motor withsaid first pipe, asecond magnet valve; for connecting said-motor" withwsaid second pipe, a pneumatic transfer switch responsive to. the difference in pressure between the fluid'in said motor and in said first-pipe and provided with a con'tachoperating member which moves .from' :one position to another position :with: ansnap actionwhen'the I diirerence, inpressure. between the fluid insaid motor andinvsaidfirstpipe: becomes-Jess than 'a first predetermined amount 'and which returns 1 s id m r-and insaidsfirsti e becomes ,less

, a second predetermined amount which is larger than said first predetermined amount, said transfer switch also being provided with a first contactwhi'chis closed when'saidcontaot operating member occupies said one position and with a second contact which is closed when said contact operating member occupies said other position, a circuit for said first magnet'valve including said first contact, and a circuit for said second magnet valve including said secondcontact.

-11. Railway braking apparatus comprising a braking'bar extending parallel. to a track rail, a fluid pressure motor for moving said braking bar toward said track rail to braking positions, a first pipe connected with a source of relatively low pressure fluid,,a second pipe connected with asource of relatively high pressure fluid, a first magnet valve for connecting said motor with said first pipe, a second magnetvalve for connecting said motor with said second pipe, a pneumatic transfer switch responsive to the diiferenceinpressure between the fluid in said motor and in said first pipe and provided with a contact operating member which moves from one position to another position'with a snap action when the difierence in pressure between the fluid in said motor and in said first pipe becomes less than a first predetermined amount and which returns .to said one position with a snap action when the difference in pressure between the fluid in said motorand in said first pipe becomes greater than a second predetermined amount which-is larger than said first predetermined amount, saidtransfer switch also being provided with a first contact which is closed when said contact operating -member'occupies said one position'and with a second contact which is closed when said contact operating member occupies said other position, a manually operable contact, a circuitfor said first valve controlled by said manually operable contactand said first'contact, and a circuit for said second valve controlled by said manually operable contactland said'second contact; a

12. Railway braking" apparatus comprising a I fluid'pressure motorv for moving said braking bar toward said track rail to braking positions, a first pipeconnected with a source of relatively low'pressure fluid, asecond pipe connected with a source of relatively'high pressure fluid, a first and a second contact, means for opening said first contact and forclosing said second contact when the difference between the pressure of the fluid in said motor and in said first pipe becomes less than. a first predetermined'amou'nt and for closing said first contact and for opening said second contact when the difference between the pressure of-the fluid insaid motor and in said first pipe becomes greater than a second predetermined amount which ismore than said first predetermined amount, a pressure responsive device subjected to the pressure of the fluid insaid motor and provided with a normally closed contact which becomes opened when the pressure of the fluid in said motor increases to a pressure which is a predetermined amount above the pressure of the fluid in said first pipe, means controlled-by said first contact and'said normally closed contact for connecting saidmotor with braking bar extending parallel to a track rail, a

bar toward said track rail to braking positions, a first pipe'connected with a source of relatively low pressure fiuid,-a second pipe connected with a source of relatively high pressure fluid, a ifirst magnet valve for connecting said motor with-said first pipe, a second magnet valve for connecting said motor with said'second pipe, a first and' asecond contact, means for opening said first contact and for closing said second'contact when the difference between the pressure of the fluid in said motor and in said firstpipe becomes less than a first predetermined amount and for-closing said first contact. andfor opening said sec-' ond contact when the difierence between the pressure of the fluid in said motor and in said first pipe becomes greater than -a second predeter mined'amount which is more than said first predetermined amount, a pressure responsive device subjected to the pressure of the fluid in said mo-. tor and provided with a normally closed contact which becomes opened when the pressure of the fluid in said motor increases to a pressure which is a predeterminedamount above the pressure of the fiuidin said first pipe, a manually operable contact; a circuit for said first valve including said first contact, said normally closed contact, and said manually operable contact; and a circuit for said second valve including said second contact, said normally closed contact, and said manually operable contact.

14. Railway braking apparatus comprising a braking bar extending parallel to a track-rail, o o

a fluid pressure motor for moving said braking bar toward said track ra'tl to braking'positions,

a first pipe connected with a source of relatively 0 low pressure fluid, a second pipe connected with a source of relatively high pressure fluid, means for at times connecting said motor with said first pipe, a first magnet valve for connecting saidlmotor with said second pipe, a second magnet valve for connecting said motor with atmosphere, a pneumatic transfer switch responsive to the pressure of the fluid in said motor and provided with a first contact which becomes opened whenthe pressure of the fluid in said motorincreases to a first pressure which is a predetermined amount higher than the pressure'of the fluid in said first pipe and which subsequently remains; opened until the pressure of the fluid in saidmo tor decreases to a second pressure which is-less braking bar extending parallel to a track rail, a 5

fluid pressure motor for moving said braking bar toward said track rail to braking positions, a first pipe connected with a 'sourceof relatively low pressure fluid, a second pipe connected with a source of relatively high pressure fluid, means for'at times connecting said motoriwith said first pipe, a first magnetvalve for connecting said motor with said second pipe, a secondmag net valve for connecting said motor with atmosphere, a pneumatictransfer switch responsive to 5 the pressure .of the fluid in said motor and providedwith a first contact which becomes opened when the pressure of the fluid in said motor in-o creases to a first pressure which is a predetermined amount higher than the pressure of the rgosigm fluid in "said first pipesandwhich, subsequently. remains opened until the pressureof the fluid in said motor decreases to'a second pressure which is'less thansaid first-pressure butmore than-the pressure of the fiuidin said first pipe, said'switch also being provided with a" second contact-which becomes closed when "said first; contact becomes opened and opened when said flrst contact. -becomes closed, and means controlled by=saidrtwo contacts "for tseleotively controlling-said i two valves.. 7 x V "'18; Railway brakin'gcapnaratus comprising a braking bar extendrngrpsrallelrto attack-rail; a fluid motor formoving said braking bar toward said track rail to braking positionsja first pipe connected-within" source or relatively low pressure fluid, a second pipe connected with a source of: relatively high ;pressin-e fluid; means for: at times --connec'ting motor "with said first pipe, a first magnetivalve forcormectingsaidimotor with said: second: pipepa sec-'- ond magnet valve-for= connecting said motor with atmosphere, ra' first contact "undersec- 0nd contactameans. for opening said first contact and for closing said second, contact when thezpressure of the -fiuid in said 'motor imcreases toa first pressure'whichis more than a predetermined amount, above the pressure of the fluid in said firsttpipe and foriclosing said first contact and for opening said second contact when pressure ofthe fluid in said motor becomes less than a second pressure which is between said first pressure and the pressure of the 1 fluid in said first pipe, I a pressure respon sive device subjected tot-he -pressure of the fluid in'said motor and providedwith a normally closed contact which becomes opened when the pressure-of? the fiuid-insaidvmotor increases-i0: a predetermined pressure: which is less thanv the 2 pressureof the fluidsin said first pipe and with a hormally open contact which "becomes closed whemthe pressure of the 'fluidai'n Lsaid 'motor increases to a'pres'sure whichis'somewhat'higha on- 'than the pressure at which said normally closed contact opens,:-a first circuit for said first magnet va'lve'including said normally closed contact, EASQCODd circuittfor said firstmagnet valve including said-second cont'actand' said normally open contaot;:and aeircuit for-saidsecoridmag- 'netvalvewincludingisaid first contact .andsaid normallya'opencontacta o r I I7.-' Railway *braking -';'apparatus braking bar extendin'g'parallel to a tracktrail, a fiuidpressure motor for'moving-said' braking bar towardsaid'trackrail *to brakingpositions,

a first pipe connected with a source or relatively- "low pressure fluida second pipe connected with a source'of relatively-high pressurefl'uid, a first magnet valve for- 'oonnectingsaid motor withsaid first pipe, a secondmagnetvalve for connecting "said motor with 'said" second pipe; a third magnet valve ror' connecting sai 'fmotor with atmosphere, a first pneum'atic" transfer switch responsive to the difireno'e in pressure between the fluid in said motor and'in said first pipe and provided with a-flrst contact operating member which moves from one position to another position with a snap'action' when the pressure of the'fluid in said motordncreases'eto a I first'pressure which is apredete'rmined amount below the pressure ofthe fluid in said first pipe and which returns-to said 'onepositiomwith' a snap action when the pressure of'the fluid "in said motor 'decreases to a second pressure which is meiow "Said first ressurwsaWfirso transfer comprising a switch being provided with a first contact which is closed'when and only when said first, contact operating member occupies its one position and;

with a, secondcontact which is closed when and only :when said first contact operating member, occupies'its other position, a second pneumatic;

transfer switch responsive to the difference in pressure between the fluid in said motor and in said first pipeiand provided with a second contactoperating' memberwhichmoves from one position toganother position with a snap action position with a snap action when the pressure;

of the fluid-in said motor decreasesbelowa fourth pressure, which is between saidi third pressure and .the pressure of the fluidin said firstpipe, said second transfer switch beingprovided with a third'contact which is; closed when and only when said second contact operating member occupies ,its one position and-with a fourth contact which is closed when and, only whensaidsecond con-tactoperating member 00- cupies its other position, means for at timesenergizing said first or said second magnet valve according as said first or said second contact is closed; and means for at other times energizing said second or said'third valve according as said fourth ,orsaid third contact is closed.

, V 18. Railway braking 3 apparatus comprising a braking barextending parallel to a; track rail, ,a. fluid pressure motor for moving said braking bar toward said track railto braking positions; a first pipe connected with a source of relatively low said first pipe and which returns to said one posi tion with a snap actionlwhen the pressure of the fluid insaid motor decreases to a'second pressure which is belowsaid first pressure; said first transferswitch beingprovided with a firstrcontact which is closed when and only when said'first contact, operating unember occupies its one position'and with a :second contact which is closed when and only when said first contact operating member occupies its other position, a second pneumatictrans'fer switch responsive to thc dife ferencein pressure between the fluid in said motor and in-said first'pi pe and provided with a second contact operating ,memberwhich moves from one; position to another position when the pressure-of the fluidin said motor increases to a 'thirdpressure which is 'a'predetermined amount above the pressureof the fluid in said first pipe and which returns to said one position with a snapuaction when the pressure ofthe fluid said -motor decreases belowa fourth pressure which is between said third pressure and the pressure ofqthe fluid in said first pipe, said second transfer switch being provided with a third contact which ;is closed when-and only when said second contact operating member "occupies its one positionaand with a fourth contact which is closed :when and only when'said secondcontact' Op rating member occupies its other position,

' second pipe, a pneumatic transfer switch responmeans for at times connecting said motor with I said first or said second pipe according assaid first or'said second contact is closed, and means for at other times connecting said motor with said first pipe or with atmosphere according as said fourth orsaid third contact is closed.

19. Railway braking apparatus comprising a braking bar adapted to engage a part of a rail-1 way car'for retarding the speed of the car, a fluid net valve'for connecting said motor with said second pipe, a pneumatic transfer switch responsive to the difference in pressure of the fluid in" said motor and said low pressure source and provided with a first contact which becomes opened when the pressure'of the fluid in 'said'motor in'* creases to a pressure which is somewhat less than the pressure of said low pressure source and with a second contact which becomes closed when said first contact becomes opened, a third contact responsive to the pressure'of the fluidin said motor and arranged to become opened when the pressure of the fluid in said motor increases to a' pressure which is somewhat-higher than the pressure of said low pressure source, two line wires, means for reversibly supplying said -.line'wires with current, means including said first contact and said third contact for at times connecting said first valve with said line wires, means including said second contact and said third contact for at other timesconnecting'said second valve :With said line wires, and means including said second contact and an asymmetric unit for at still other times connecting said second-valve with said line-Wires. r

20. Railway braking apparatus comprising a braking bar adapted to engage a part of a railway car for retardingthe speed of the car, a fluidpressure motor for moving said braking bar to braking positions, a first pipe connected with a source of relatively low pressure fluid, a'second pipe connected with a source of relatively high pressure fluid, a first magnet valve for connecting said motor with said first pipe, a second magnet valve'for connecting said motor with said sive' to the difference between thepressure of the fluid in said motor and said first'pipe and provided with a first contact which becomes opened when the pressure of the fluid'in said motor increases to a pressure which is somewhat less than the pressure of said low pressure source and with a second contact which'becor'nes closed when said first contact becomesopened, a pressure responsive device subjected to the pressure of thefluid'in said motor and provided with a'normal- 1y closed contact which becomes opened when the pressure of the fluid in said motor increases to a pressure which'is somewhat higher than the pressure of said low pressure sourceand with a normally open contact which becomes closed at a pressure which is somewhat higher'than the pressure at which said normally closed contact opens, two line wires, means for reversibly 'sup-' plying sai'dline wires with current, means including said normallyclosed contact and said first contact for connecting said first magnet valve with said line wires, means including saidnormally closed contact and said first contact for connecting said second magnet valve with 'said second magnet valve with said line wires,'a'nd means including said normally open contact and 'a second asymmetric unit? for connecting said first magnet'valve with said-line wires.

21. Railway braking apparatus comprising, a braking bar extending parallel to a track rail, a fluid pressure motor for moving .said braking bar toward said track rail to'braking positions, a first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively"high'pressure fiuid, ,a..first magnet valverfor connecting said motor with said first pipe, a second magnet'valve for connecting said motor with said second pipe, a pneumatic transfer switch responsiveto the difference in pressure between the fluid insaid motor andin said first pipelandi provided with a contact operating member which moves from .one position to another position with a snap action when' the difference in pressure between the'fluid in,

said motor and in said first pipe becomes less than a first predetermined amount andwhichreturns tosaid one position with a snap action when the difference in pressure between the fluid in said motor and in said first pipe becomes greater than a second predetermined amount which is larger than said first predetermined amount, said transfer switch also being provided with a first contact which is closed when said contact operating member. occupies said one position and with. a second contactwhich is closedwhensaid contact operating memberfoccupies. said other posi-' tion, a third contact "responsive to the pressure of the fluid in said-motor and arranged'to become opened when the-pressure of the-fluid in said motor increases to. apressure which is somewhat higher than the pressure. of said :low pressure source, two:.line wires, mean'sifor :reversibly. supplying said line wires with current, means' ineluding said first contact and 'saidthirdcontact for at timesconnecting said first valve with said line wires, means including said second-icontact and said third contact for at-other times and means including said second contact-and an connecting said second valve-with said'line wires; :1;-

as'ymmetric unit forat still iotheritimes connecting said second valve withsaid' line wires.

, 22. Rai1way t'brakin'g apparatus comprising a braking bar extending parallel to a trackrail, a fluid pressure motor -for moving said zbraking bar toward said track rail ,to braking positions, a first pipe connected ,with .a source of relatively low pressurefiuid, asecond pipeconnect'ed with for at timesconnecting said motor with said see 1a source of relatively high pressure fluid, means 0nd pipe, a first magnet valve forconnecting said motor with said first pipe, a second magnet-valve for. connectingsaid motor-with atmosphera'a pneumatic transfer switch responsive to the pressure of the fluid in said motor and provided with a first contact which becomes opened when the pressure of the fluid in said motor increases to a first {pressure which is a; predetermined amount higher than the pressure of the fiu'id in i comes closed, twoline wires, me an s for reversibly cluding a second asymmetric unit for at still other times connecting said first valve with said line wires, said first and second asymmetric units beingdisposed in opposite directions with respect to said line wires.

HAROLD C. CLAUSEN. 

